This invention relates to the process for manufacturing bulked continuous filaments of poly(trimethylene terephthalate), to the resulting filaments and to carpets made from the bulked filaments
Carpets which are resistant to staining by common food dyes are currently in high demand. In order to be stain-resistant, nylon carpets must either be treated with a stain-resist chemical or the nylon fibers must have a stain-resist agent incorporated within the polymer.
However, carpets made from polyester fibers have the benefit of the natural stain-resistant properties of polyester. Polyester carpets are commonly made from filaments of poly(ethylene terephthalate). These carpets may have poor crush resistance (also called pile height retention) and poor texture retention (i.e., the yarns in the tuft tips unravel with wear). Carpets may develop a matted appearance in areas of high foot traffic.
Polyester carpets have also been made from filaments of poly(butylene terephthalate). While these carpets may have improved resistance to crushing vs. carpets of poly(ethylene terephthalate), the carpets may exhibit poor initial texture and poor texture retention.
It would therefore be useful to have a polyester carpet which has natural, built-in stain-resistance and, at the same time, adequate texture retention and resistance to crushing.
One embodiment of the present invention is a carpet made from bulked continuous filament (BCF) yarn of poly(trimethylene terephthalate). The carpets have built-in stain-resistance and a texture retention and resistance to crushing which is superior to that of carpets made from similar BCF yarns of poly(ethylene terephthalate) or poly(butylene terephthalate). The carpets of this invention are tufted with crimped ply-twisted yarns made from multiple bulked continuous filaments having random 3-dimensional curvilinear crimp, a boil off bundle crimp elongation (BCE) (as later defined herein) between 20-95 percent and a shrinkage (as later defined herein) from 0 to 5 percent. The filaments are made from poly(trimethylene terephthalate) having an intrinsic viscosity between about 0.6 to 1.3.
A second embodiment of this invention is the poly(trimethylene terephthalate) BCF yarn used to make the carpets of this invention. The bulked continuous filament yarns of this invention have an intrinsic viscosity between 0.6 to 1.3, a boil off BCE between 20 to 95 percent, a shrinkage from 0 to 5 percent, a denier per filament between 4 and 25 and a total denier between 700 and 5000. Tenacity is in the range of 1.2 to 3.5 grams per denier (gpd) and break elongation is between 10 to 90 percent, preferably 20 to 70 percent.
A third embodiment of this invention is the process for manufacturing the BCF yarn. The overall process comprises the steps of:
a) extruding molten poly(trimethylene terephthalate) polymer at a temperature between 245xc2x0 C. to 285xc2x0 C. through a spinneret to form filaments, said poly(trimethylene terephthalate) polymer having an intrinsic viscosity in the range of 0.6 to 1.3 and a water content of less than 100 ppm by weight;
b) cooling the filaments by means of air flowing perpendicularly to the filaments at a velocity in the range of 0.2 to 0.8 m/sec.;
c) coating the filaments with a spin finish;
d) heating the filaments to a temperature greater than the glass transition temperature of the filaments, but less than 200xc2x0 C. prior to drawing the filaments;
e) drawing the filaments between a set of feed rolls and a set of draw rolls to a draw ratio high enough that the break elongation of the drawn filaments is between 10 to 90%, the temperature of the draw rolls being from 120xc2x0 to 200xc2x0 C.;
f) feeding the drawn filaments from the draw rolls at a speed of at least 800 in/mm. to a bulking unit in which the filaments are blown and deformed in three dimensions with hot bulking fluid having a temperature at least as high as that of the draw rolls to form bulked continuous filaments having randomly spaced curvilinear crimp;
g) cooling the bulked continuous filaments to a temperature less than the glass transition temperature of the filaments; and
h) winding up the filaments at a speed at least 10% lower than that of the draw rolls.